Optical Coherent Tomography (OCT) using an interference phenomenon of multi-wavelength light is a method for acquiring a tomographic image of a sample (particularly the fundus) with a high resolution. An apparatus for imaging a tomographic image by using such OCT is hereinafter called “an OCT apparatus”. Recently, by enlarging the beam diameter of a measuring beam in an OCT apparatus of the Fourier Domain system, a tomographic image of the retina can be provided with an improved lateral the resolution. However, as the beam diameter of the measuring beam has been enlarged, there is, at acquisition of a tomographic image of the retina, presented a problem of decrease in the S/N ratio and resolution of the tomographic image due to an aberration in an eye to be inspected. To resolve the problem, an adaptive optics OCT apparatus having adaptive optics has been developed in which an aberration in an eye to be inspected is measured by a wavefront sensor in real time, the aberration, generated in the eye to be inspected, of a measuring beam or a return beam are corrected by a wavefront correcting device, and thereby the apparatus enables a tomographic image being provided with a high lateral resolution.
Regarding an apparatus using such adaptive optics, Japanese Patent Application Laid-Open No. 2007-14569 proposes an ophthalmologic imaging apparatus capable of acquiring an image of the fundus by using adaptive optics, a polygon mirror, a galvano-mirror, etc. in a scanning laser ophthalmoscope (SLO apparatus). This ophthalmologic imaging apparatus is adapted so that an aberration in an eye to be inspected is detected and an aberration of a return beam formed of a measuring beam irradiated to a retina is corrected by using the adaptive optics, and allows a lateral resolution to be prevented from being degraded. Also, “Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction”, Opt. Express 16, 8126 (2008) describes an OCT apparatus of the Fourier Domain system in which both of a high lateral resolution and a high longitudinal resolution are intended to be coexistent by using the adaptive optics and a chromatic aberration correction lens. Here, it is tried to reduce speckles and improve the contrast of a tomographic image by measuring and correcting an aberration of a measuring beam and a return beam generated in an eye to be inspected using the adaptive optics, and further averaging obtained tomographic images of the retina.